Mechanics of Panic

A panicking crowd can be a prelude to death, as recent rock-concert and soccer-stadium casualties attest. But it needn't be, says engineer and physicist Dirk Helbing of Dresden University of Technology in Germany. According to his computer models, small design changes could make all the difference between calamitous crush and peaceful passage.

Previous attempts to simulate the behavior of frenzied crowds treated people as if they were fluids pouring smoothly out of water pipes. But panicking groups trip, shove, and build up blockages that gather enough force to bend steel barriers or break down brick walls. Helbing's simulation designed with physicists Tamás Vicsek and Illés Farkas of Eötvös University in Budapest adds realistic human interactions.

The model shows that when people panic, they move faster and switch direction at random more frequently than they would otherwise. Such behavior increases the likelihood that they will bump into one another and create obstructions in tight spaces. Eliminating bottlenecks and highlighting optimal escape routes helps, but Helbing's simulation led to another idea. Small concrete columns, set back from exits, would absorb pressure from people pushing behind, reducing injuries and increasing outflow by up to 50 percent. Helbing also has a tip for people caught in a panic: "Don't automatically do what everyone is doing. Follow small groups, keep a distance from other people, and look for alternative exits." In short, don't go with the flow.